Develop Reference

How can I convert timestamp to date format yyyy-MM-dd'T'HH:mm:ssXXX?

I would like to know if there's a way to convert a timestamp to yyyy-MM-dd'T'HH:mm:ssXXX date format?
I can convert it to ISO using toISOString but it add Z at the end of the string.
Thank you.

var d = new Date();
var datestring = d.getDate() + "-" +
(d.getMonth() + 1) + "-" +
d.getFullYear() + "-T " +
d.getHours() + ":" +
d.getMinutes();

If you really do not want to use an external library like moment.js (which i would strongly recommend), as you stated in your comment, you will have to implement a function for that yourself, as regular javascript does not provide a function for this (as far as i know).
You can create an object of javascripts built-in Date class from a unix timestamp by using
var unixTimestamp = 1566394163;
//multiply with 1000 as Date expects milliseconds
var date = new Date(unixTimestamp * 1000);
Then you could build the output string yourself, by using something along this
var dateString = "";
dateString += date.getUTCFullYear()+"-";
dateString += date.getUTCMonth()+"-";
dateString += ...
On the other hand, if the Z at the end of the string is the only thing that bothers you about the format provided by toISOString() as a workaround you could use its output and remove the last character of it
var dateString = date.toISOString();
var newDateString = dateString.substr(0, dateString.length -1);

Please try using below code to convert timestamp to date format.
var date = new Date(timestamp*1000);
var year = date.getFullYear();
var month = months_arr[date.getMonth()];
var day = date.getDate();
var hours = date.getHours();
var minutes = "0" + date.getMinutes();
var seconds = "0" + date.getSeconds();
Display date time in any format you want.

Javascript setting date format including 0 with date and month

Essentially I am trying to convert a date such as 2019-02-09 to 09-02-2019. I have the following:
var newDate = new Date('2019-02-09');
strDate = newDate.getDate() + "-" + (newDate.getMonth() + 1) + "-" + newDate.getFullYear();
which works but will output 9-2-2019. Is there a neat method (ie not checking getDate and getMonth less than 10) to get the output 09-02-2019?

Using toLocaleDateString():
var dt = new Date('2019-02-09');
var x = dt.toLocaleDateString('en-US', { year: 'numeric', month: '2-digit', day: '2-digit' })
.replace(/[^0-9]/g, '-');
console.log(x);

Just use the toLocaleDateString() method and choose en-GB as the locale to return your date in the DD/MM/YYYY format and use a simple split() and join() or regex to replace / with - like this:
Split and Join approach:
var newDate = new Date('2019-02-09');
strDate = newDate.toLocaleDateString('en-GB').split("/").join("-");
alert(strDate);
Regex:
var newDate = new Date('2019-02-09');
strDate = newDate.toLocaleDateString('en-GB').replace(/[^0-9]/g, '-');
alert(strDate);

You could use padStart to achieve your goal.
var newDate = new Date('2019-02-09');
strDate = newDate.getDate().toString().padStart(2, "0") + "-" + (newDate.getMonth() + 1).toString().padStart(2, "0") + "-" + newDate.getFullYear();
console.log(strDate);

Converting string m/dd/yyyy HH:MM:SS to date dd-mm-yyyy in Javascript

I have a string that looks like '1/11/2018 12:00:00 AM' and I want to reformat it to dd-mm-yyyy.
Keep in mind that the month can be double digit sometimes.

You can use libraries like moment.js. Assuming either you do not want to use any external library or can not use it, then you can use following custom method:
function formatDate(dateStr) {
let date = new Date(dateStr);
let day = date.getDate();
let month = date.getMonth() + 1;
let year = date.getFullYear();
return day + '-' + month + '-' + year;
}
console.log(formatDate('1/11/2018 12:00:00 AM'));

You can do somethink like this :
var d = new Date();
var curr_date = d.getDate();
var curr_month = d.getMonth() + 1; //Months are zero based
var curr_year = d.getFullYear();
console.log(curr_date + "-" + curr_month + "-" + curr_year);
However best way is with Moment.js,where you can Parse, Validate, Manipulate, and Display dates in JavaScript.
example:
var date= moment("06/06/2015 11:11:11").format('DD-MMM-YYYY');

function convertDate(oldDate) {
var myDate = new Date(Date.parse(oldDate)); //String -> Timestamp -> Date object
var day = myDate.getDate(); //get day
var month = myDate.getMonth() + 1; //get month
var year = myDate.getFullYear(); //get Year (4 digits)
return pad(day,2) + "-" + pad(month, 2) + "-" + year; //pad is a function for adding leading zeros
}
function pad(num, size) { //function for adding leading zeros
var s = num + "";
while (s.length < size) s = "0" + s;
return s;
}
convertDate("1/11/2018 12:00:00 AM"); //11-01-2018
Demo here

Javascript format date

I have a date string which coming from the db as follows
/Date(1469167371657)/
Is there any way to convert this date to following format using javascript
MM/DD/YYYY HH:MM
I've searched a lot but unble to find a solution

In plain javascript you have to write your own function for string format a date, for example for your string format:
var date = new Date(1469167371657);
function stringDate(date) {
var mm = date.getMonth()+1;
mm = (mm<10?"0"+mm:mm);
var dd = date.getDate();
dd = (dd<10?"0"+dd:dd);
var hh = date.getHours();
hh = (hh<10?"0"+hh:hh);
var min = date.getMinutes();
min = (min<10?"0"+min:min);
return mm+'/'+dd+'/'+date.getFullYear()+" "+hh+":"+min;
}
console.log(stringDate(date));
drier code version
var date = new Date(1469167371657);
function stringDate(date) {
return ("0" + (date.getMonth() + 1)).slice(-2)+'/'
+("0" + date.getDate()).slice(-2)+'/'
+date.getFullYear()+" "
+("0" + date.getHours()).slice(-2)+':'
+("0" + date.getMinutes()).slice(-2)
}
console.log(stringDate(date));

with pure js you can do the folowing
var d = new Date();
console.log(d.getMonth() + 1 + "/" + d.getDate() + "/" + d.getFullYear() + " " + d.getHours() + ":" + d.getMinutes())

You can use - http://momentjs.com/ and have it done like:
moment(1469167371657).format('MM/DD/YYYY HH:MM')

You can do this with the following steps:
1) convert the timestamp to a date object.
var timestamp = "/Date(1469167371657)/"; // However you want to save whatever comes from your database
timestamp = timestamp.substr(timestamp.indexOf("(")+1); // gives 1469167371657)/
timestamp = timestamp.substr(0,timestamp.indexOf(")")); // gives 1469167371657
var d = new Date(timestamp);
2) set it to your format
function leadZero(i) {if(i < 10) {return "0"+i;} return i;} // Simple function to convert 5 to 05 e.g.
var time = leadZero(d.getMonth()+1)+"/"+leadZero(d.getDate())+"/"+d.getFullYear()+" "+leadZero(d.getHours())+":"+leadZero(d.getMinutes());
alert(time);
Note: the date / timestamp you provided is too high for javascript to understand, so this example will not work correclty

I believe that number is milliseconds so to convert it to date, you would do this:
var time = new Date().getTime();
var date = new Date(time);
alert(date.toString()); // Wed Jan 12 2011 12:42:46 GMT-0800 (PST)
var time=1469167371657;
var date = new Date(time);
alert(date.toString());

Combine date and time string into single date with javascript

I have a datepicker returning a date string, and a timepicker returning just a time string.
How should I combine those into a single javascript Date?
I thought I found a solution in Date.js. The examples shows an at( )-method, but I can't find it in the library...

You can configure your date picker to return format like YYYY-mm-dd (or any format that Date.parse supports) and you could build a string in timepicker like:
var dateStringFromDP = '2013-05-16';
$('#timepicker').timepicker().on('changeTime.timepicker', function(e) {
var timeString = e.time.hour + ':' + e.time.minute + ':00';
var dateObj = new Date(datestringFromDP + ' ' + timeString);
});
javascript Date object takes a string as the constructor param

Combine date and time to string like this:
1997-07-16T19:20:15
Then you can parse it like this:
Date.parse('1997-07-16T19:20:15');
You could also use moment.js or something similar.

For plain JavaScript:
combineDateAndTime = function(date, time) {
timeString = time.getHours() + ':' + time.getMinutes() + ':00';
var year = date.getFullYear();
var month = date.getMonth() + 1; // Jan is 0, dec is 11
var day = date.getDate();
var dateString = '' + year + '-' + month + '-' + day;
var combined = new Date(dateString + ' ' + timeString);
return combined;
};

You can concatenate the date and time, and then use moment to get the datetime
const date = '2018-12-24';
const time = '23:59:59';
const dateTime = moment(`${date} ${time}`, 'YYYY-MM-DD HH:mm:ss').format();

Boateng's example fails in cases where time consisted of hours, minutes, days or months that ranged from values 0-9 as getDate(), getMonth() etc... will return 1 digit in these cases and the time string will fail and an invalid date is returned:
function CombineDateAndTime(date, time) {
const mins = ("0"+ time.getMinutes()).slice(-2);
const hours = ("0"+ time.getHours()).slice(-2);
const timeString = hours + ":" + mins + ":00";
const year = date.getFullYear();
const month = ("0" + (date.getMonth() + 1)).slice(-2);
const day = ("0" + date.getDate()).slice(-2);
const dateString = "" + year + "-" + month + "-" + day;
const datec = dateString + "T" + timeString;
return new Date(datec);
};
Unfortunately do not have enough rep to comment

David's example with slight modifications:
function CombineDateAndTime(date, time) {
var timeString = time.getHours() + ':' + time.getMinutes() + ':00';
var ampm = time.getHours() >= 12 ? 'PM' : 'AM';
var year = date.getFullYear();
var month = date.getMonth() + 1; // Jan is 0, dec is 11
var day = date.getDate();
var dateString = '' + year + '-' + month + '-' + day;
var datec = dateString + 'T' + timeString;
var combined = new Date(datec);
return combined;
};

Concate date and time with moment JS which also works on firefox,
let d1 = moment().format('MM/DD/YYYY');
let dateTimeOpen = moment(d1 + ' ' + model.openingTime).format('YYYY-MM-DD HH:mm:ss');
let dateTimeClose = moment(d1 + ' ' + model.closingTime).format('YYYY-MM-DD HH:mm:ss');

const date = "2022-12-27";
const time = "16:26:42";
new Date(`${date}T${time});
output
Date Tue Dec 27 2022 16:26:42 GMT+0100 (Central European Standard Time)